The occlusion of body cavities, blood vessels, and other lumina by embolization is desired in a number of clinical situations. For example, the occlusion of fallopian tubes for the purposes of sterilization, and the occlusive repair of cardiac defects, such as a patent foramen ovale, patent ductus arteriosis, and left atrial appendage, and atrial septal defects. The function of an occlusion device in such situations is to substantially block or inhibit the flow of bodily fluids into or through the cavity, lumen, vessel, space, or defect for the therapeutic benefit of the patient.
The embolization of blood vessels is also desired in a number of clinical situations. For example, vascular embolization has been used to control vascular bleeding, to occlude the blood supply to tumors, and to occlude vascular aneurysms, particularly intracranial aneurysms. In recent years, vascular embolization for the treatment of aneurysms has received much attention. Several different treatment modalities have been shown in the prior art. One approach that has shown promise is the use of thrombogenic microcoils. These microcoils may be made of biocompatible metal alloy(s) (typically a radio-opaque material such as platinum or tungsten) or a suitable polymer. Examples of microcoils are disclosed in the following patents: U.S. Pat. No. 4,994,069 to Ritchart et al.; U.S. Pat. No. 5,133,731 to Butler et al.; U.S. Pat. No. 5,226,911 to Ghee et al.; U.S. Pat. No. 5,312,415 to Palermo; U.S. Pat. No. 5,382,259 to Phelps et al.; U.S. Pat. No. 5,382,260 to Dormandy, Jr. et al.; U.S. Pat. No. 5,476,472 to Dormandy, Jr. et al.; U.S. Pat. No. 5,578,074 to Mirigian; U.S. Pat. No. 5,582,619 to Ken; U.S. Pat. No. 5,624,461 to Mariant; U.S. Pat. No. 5,645,558 to Horton; U.S. Pat. No. 5,658,308 to Snyder; and U.S. Pat. No. 5,718,711 to Berenstein et al.; all of which are hereby incorporated by reference.
A specific type of microcoil that has achieved a measure of success is the Guglielmi Detachable Coil (“GDC”), described in U.S. Pat. No. 5,122,136 to Guglielmi et al. The GDC employs a platinum wire coil fixed to a stainless steel delivery wire by a solder connection. After the coil is placed inside an aneurysm, an electrical current is applied to the delivery wire, which electrolytically disintegrates the solder junction, thereby detaching the coil from the delivery wire. The application of current also creates a positive electrical charge on the coil, which attracts negatively-charged blood cells, platelets, and fibrinogen, thereby increasing the thrombogenicity of the coil. Several coils of different diameters and lengths can be packed into an aneurysm until the aneurysm is completely filled. The coils thus create and hold a thrombus within the aneurysm, inhibiting its displacement and its fragmentation.
Alternative vaso-occlusive devices are exemplified in U.S. Pat. No. 6,299,619 to Greene, Jr. et al.; U.S. Pat. No. 6,602,261 to Greene, Jr. et al.; U.S. Pat. No. 6,605,101 to Schafer et al.; U.S. Pat. No. 7,029,486 to Schaefer et al.; U.S. Pat. No. 7,033,374 to Schaefer et al.; U.S. Pat. No. 7,331,974 to Schaefer et al.; and in co-pending U.S. patent application Ser. No. 10/631,981 to Martinez; U.S. patent application Ser. No. 11/398,081 to Schaefer et al.; and U.S. patent application Ser. No. 11/398,082 to Schaefer et al., all of which are assigned to the assignee of the subject invention and incorporated herein by reference.
There is, however, an ongoing need to provide more advanced and improved neuro-embolic microcoils that exhibit greater stability after deployment in a target site; improved space seeking ability within the target site; wider application for treatment of target sites of varying sizes; and increased efficacy for treating and occluding the target site.